In a liquid crystal display device, a classification based on an operating mode for liquid crystal molecules includes a phase change (PC) mode, a twisted nematic (TN) mode, a super twisted nematic (STN) mode, an electrically controlled birefringence (ECB) mode, an optically compensated bend (OCB) mode, an in-plane switching (IPS) mode, a vertical alignment (VA) mode, a fringe field switching (FFS) mode and a field-induced photo-reactive alignment (FPA) mode. A classification based on a driving mode in the device includes a passive matrix (PM) and an active matrix (AM). The PM is classified into static, multiplex and so forth, and the AM is classified into a thin film transistor (TFT), a metal insulator metal (MIM) and so forth.
A liquid crystal composition is sealed into the device. Physical properties of the composition are associated with characteristics of the device. Specific examples of the physical properties in the composition include stability to heat and light, a temperature range of a nematic phase, viscosity, optical anisotropy, dielectric anisotropy, specific resistance and an elastic constant. The composition is prepared by mixing a large number of liquid crystal compounds. The physical properties required for the compound include high stability to an environment such as water, air, heat and light, a wide temperature range of a liquid crystal phase, small viscosity, suitable optical anisotropy, large dielectric anisotropy, a suitable elastic constant, satisfactory compatibility with other liquid crystal compounds. A compound having high maximum temperature of a nematic phase is preferred. A compound having low minimum temperature in the liquid crystal phase such as the nematic phase and a smectic phase is preferred. A compound having small viscosity contributes to a short response time in the device. A suitable value of optical anisotropy is different depending on a mode of the device. In order to drive the device at a low voltage, a compound having large positive or negative dielectric anisotropy is preferred. In order to prepare the composition, a compound having satisfactory compatibility with other liquid crystal compounds is preferred. The device may be occasionally used at a temperature below a freezing point, and therefore a compound having satisfactory compatibility at a low temperature is preferred.
A great number of liquid crystal compounds have been so far prepared. Development of a new liquid crystal compound is still continued. The reason is that satisfactory physical properties that are not found in a conventional compound are expected in a new compound. The reason is also that the new compound provides at least two physical properties in the composition with a suitable balance in several cases. Only a limited number of reports has been found on a compound having divalent group (pr-I) described below.

WO 2007/066755 A (Patent literature No. 1) discloses a compound represented by No. 298 on page 42. The compound is abbreviated as comparative compound (298). See Comparative Example 1.

JP 2006-520327 A (Patent literature No. 2) discloses a compound represented by No. 121 on page 87. The compound is abbreviated as comparative compound (121). See Comparative Example 1.

The Journal Organic Chemistry, 2012, 77, 2331-2336 (Non-patent literature No. 1) and The Journal Organic Chemistry, 2012, 77, 5022-5029 (Non-patent literature No. 2) disclose a compound having an isocoumarin skeleton (for example, the compound described below).
